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Shikaze, Yoshiaki
Radioisotopes, 74(3), p.273 - 287, 2025/11
The previous method used the data during the stable period for the position and attitude angles of the unmanned helicopter as a countermeasure to improve the measurement data analysis of the Compton camera system mounted on the unmanned helicopter. However, this reduced the number of events used for analysis, allowing statistical accuracy to be improved in future. Therefore, all event data were corrected and used this time. The scintillator coordinates of two layers fixed in the previous analysis were replaced with those corrected for the ever-changing positions and tilts for each event. I reconstructed gamma-ray images using the corrected events to improve their statistical accuracy and spatial resolution. I compared the ground measurement results to evaluate the improvement in the accuracy of the reconstructed images of gamma-ray intensity. As for the effect of the improved statistics, a decrease in the residual sum of squares (RSS) was noted after improvement, indicating the effectiveness of this method through good correlations with the ground-measured values. Moreover, from the RSS value comparison, compared to changing from the previous method to the improved method, expanding the range of averaging the measured values was confirmed to be more effective, showing better correlations with the ground-measured values.
Shikaze, Yoshiaki; Shimazoe, Kenji*
Journal of Nuclear Science and Technology, 59(1), p.44 - 54, 2022/01
Times Cited Count：4 Percentile：37.40(Nuclear Science & Technology)A Compton camera system for use on an unmanned helicopter was previously developed for characterizing the distribution of radioactive materials in highly contaminated areas. For this study, a small camera, a laser distance meter, an attitude angles sensor, temperature sensors, and real-time monitoring software were equipped to the Compton camera system to better measure flight parameters and to more precisely detect hot spot locations. To confirm if detection results were improved by the modifications, measurements were taken from hovering and programmed flights over a field in Okuma, Fukushima Prefecture (Japan). Ambient dose equivalent rate distributions at ground level were obtained by processing the flight data, then compared against measurements taken at ground level on foot using a survey meter. For one hovering flight, the correlation between the datasets was improved by selecting a period of stable flight position and attitude, and by restricting the deviation of the attitude angles. Between 6.0%-7.6% improvement in the position resolution was achieved by using the data from stable flight periods, even when using 1 minute data windows. The precision of hot spot detections and ambient dose equivalent rate distributions obtained from the Compton camera were thus improved by the aforementioned modifications to the system.
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scintillator Compton camera mounted on an unmanned helicopterShikaze, Yoshiaki; Nishizawa, Yukiyasu; Sanada, Yukihisa; Torii, Tatsuo; Jiang, J.*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Yoshino, Masao*; Ito, Shigeki*; Endo, Takanori*; et al.
Journal of Nuclear Science and Technology, 53(12), p.1907 - 1918, 2016/12
Times Cited Count：41 Percentile：95.84(Nuclear Science & Technology)The Compton camera was improved for use with the unmanned helicopter. Increase of the scintillator array from 4
4 to 88 and expanse of the distance between the two layers contributed to the improvements of detection efficiency and angular resolution, respectively. Measurements were performed over the riverbed of the Ukedo river of Namie town in Fukushima Prefecture. By programming of flight path and speed, the areas of 65 m 60 m and 65 m 180 m were measured during about 20 and 30 minutes, respectively. By the analysis the air dose rate maps at 1 m height were obtained precisely with the angular resolution corresponding to the position resolution of about 10 m from 10 m height. Hovering flights were executed over the hot spot areas for 10-20 minutes at 5-20 m height. By using the reconstruction software the 
-ray images including the hot spots were obtained with the angular resolution same as that evaluated in the laboratory (about 10
).
Shikaze, Yoshiaki; Torii, Tatsuo; Nishizawa, Yukiyasu; Yoshida, Mami*; Shimazoe, Kenji*; Jiang, J.*; Takahashi, Hiroyuki*; Kurosawa, Shunsuke*; Kamada, Kei*; Yoshikawa, Akira*; et al.
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Shikaze, Yoshiaki; Shimazoe, Kenji*
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Shikaze, Yoshiaki
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Shikaze, Yoshiaki; Torii, Tatsuo; Shimazoe, Kenji*; Jiang, J.*; Takahashi, Hiroyuki*; Kurosawa, Shunsuke*; Kamada, Kei*; Yoshikawa, Akira*; Yoshino, Masao*; Ito, Shigeki*; et al.
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Sasaki, Miyuki; Nishizawa, Yukiyasu; Imura, Mitsuo; Yamada, Tsutomu; Sanada, Yukihisa
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